Device for performing a photoelectrochemical method of separating water into hydrogen and oxygen

ABSTRACT

The invention is directed to a system for hydrogen production from water, known as a photoelectrochemical system. The system integrates a semiconductor material and a water electrolyzing material inside a monolithic design, to produce hydrogen directly from water. Natural or synthetic light is used as the main or sole source of energy. The water electrolyzing material is melanins, melanin precursors or melanin derivatives, melanin variants, melanin analogues, natural or synthetic, pure or mixed with organic or inorganic compounds, metals, ions, drugs. The system or light absorbing compound generates enough energy to start, lead and complete the photoelectrolysis reaction. The system can generate hydrogen, oxygen and high energy electrons, and can synthesize water from the union of hydrogen and oxygen, thereby generating electricity. The system can also be coupled to other processes, generating a multiplication effect, and can be used for the reduction of carbon dioxide, nitrates, sulphates and the like.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser.No.12/001,138, filed Dec. 10, 2007, now U.S. Pat. No. 8,455,145, issuedJun. 4, 2013, which was a Continuation-in-Part of InternationalApplication No. PCT/MX2005/000092, filed Oct. 13, 2005, and thedisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to the processes or methods for obtainingalternative energy, particularly the ones known as photoelectrochemicalprocesses, through which hydrogen and oxygen atoms are obtained by meansof the separation or partition of water molecule with which we generatehydrogen and oxygen atoms. Moreover, high energy electrons aregenerated, and very possibly this method can be applied to the reductionof carbon dioxide, nitrate and sulphate molecules.

-   Because the reactions occur in both ways, our invention can also be    applied to electricity generation, for our method permits to bind    hydrogen and oxygen atoms forming water molecules, and collaterally    generating electrical current.

BACKGROUND OF THE INVENTION

About the related art, nowadays, the known processes used up to now toseparate the water molecule in hydrogen and oxygen atoms are, amongothers:

-   a).—The application of intense electrical currents.-   b).—The heating of water until two thousand degrees centigrade.-   c).—The separation of water molecule by solar electrochemical    method: (photoelectrochemical), which integrates a semi-conductor    material and a water electrolyzer in a monolithic design to produce    hydrogen directly from water using light as the unique energy    source. Simple in concept, the challenge was to find a material or    base that could support the whole process, and up to now, the ideal    or the most adequate material had not found because some materials    are very expensive, some are polluting, others are inefficient; most    of them decompose fast, others are damaged with water and some    others require exceedingly strict work conditions; that is why    cost-effectiveness has not been feasible up to now from an    economical, environmental and political point of view, and others    are not appropriate for large scale application, their usefulness    being thus reduced to some specific and small processes-   d).—Another method to separate water is by solar energy    concentration (with mirrors for example), with the object to elevate    water temperature until two thousand ° C. This is the required    temperature used in laboratory to divide the water molecule.-   e).—One further method is by using photosynthetic microbes as green    algas and cianobacterium, those produce hydrogen from water as part    of metabolic activities using light energy as main source. This    photobiological technology is promising, but as oxygen is produced    as well as hydrogen, the technology must solve the limitation that    is the sensibility to oxygen in the enzymatic systems. Besides,    hydrogen production from photosynthetic organisms is currently too    low to be economically viable.-   f).—Another method is water electrolysis, using electricity to    separate the water molecule in its compounds (hydrogen and oxygen    atoms). At present time, two kinds of electrolyzers are used for    commercial production of hydrogen: the alkaline, and the membrane of    protons interchange, but these approaches cannot compete now from an    economic point of view with the hydrogen produced from natural gas.    (Source: U.S. Department of Energy, Efficiency and Renewable    Hydrogen fuel cells and Infrastructure Technology Program Hydrogen    Production & Delivery).

A natural material that can also divide or separate the water moleculeand that has been studied is chlorophyll but because its affinity withlight is between 400 nm and about 700 nm the rest of the light energy islost. That is why it is estimated that 80 percent of used energy iswasted. Moreover, its production is complex and expensive, requiring forexample temperatures of −8° C. These are the reasons by which we decidedto use the melanins as electrolyzing water element, because its affinityin the spectrum goes from 200 to 900 nm or more, and because of thephysiological characteristics of the tissues in which melanin generallyoccurs. Parameters such as the oxygen concentration call the attentionand that is why we decided to contrast the hypothesis that when melaninis illuminated, we would get the photolysis of the water molecules,generating thus oxygen and hydrogen atoms, besides other products suchas OH, hydrogen peroxide, anion superoxide and high energy electrons, aswell as support and catalyze the reverse reaction.

Before our work, the photohydrolitic and hydrosynthetic properties ofmelanin, the so called melanin response to electrorretinogram only hadhistorical interest. In the early sixties, it was discovered thatintense non physiological luminous stimulus applied to the pigmentedephythelium of the retina, generated potential changes throughout it.This response to melanin reflects a physicochemical response to lightabsorption by melanin, similar in some way to the early potential ofelectrorretinogram receptors generated by opsin molecules.

The literature points out that researchers have not found the clinicalapplication to the melanin response yet. And we add that this is due tothe fact that the process of said event had not been understood. Now weknow that portions surrounding the molecule collect photon energy andthrough it the water molecule is divided, that is, they oxide it,separating hydrogen from oxygen, then the hydrogen, the carrier ofenergy by excellence is caught possibly by FAD and NAD for its furtherprocessing by eukaryote cell to energize one or other reaction among themany that occur every second and lead to life. But the wonder of theevent is that also the structure of (primary, secondary, third, fourth)melanin permits the occurrence of the opposite reaction, i.e. the unionof hydrogen and oxygen, or in other words, the reduction of oxygen, thatproduces water and electricity. The absorption of light by the melaninstarts an ionic event that finally gives us electricity, because thesole division of water molecule is not enough; the reversibility of thereaction has to happen, i.e. the reunion of the hydrogen and oxygenatoms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Any range or ranges disclosed in this description are deemed to includeand provide support for any sub-range within those range or ranges. Anyrange or ranges disclosed in this description are deemed to include andprovide support for any point or points within those range or ranges.

This invention consists essentially in obtaining under normaltemperature, and using natural or artificial light, as the only sourceof energy, the division of water molecule to obtain hydrogen and oxygenatoms as well as electrons of high energy or join hydrogen or oxygenatoms to obtain water and electric current; using as main or centralelectrolyzing melanin, melanin precursors, melanin derivatives andmelanin analogues: polihydroxyindole, eumelanin, feomelanin, alomelanin,neuromelanin, humic acid, fulerens, graphite, polyindolequinones,acetylene black, pyrrole black, indole black, benzene black, thiopheneblack, aniline black, poliquinones in hydrated form sepiomelanins, dopablack, dopamine black, adrenalin black, catechol black, 4-amine catecholblack, in simple linear chain, aliphatics or aromatics; or theirprecursors as phenoles, aminophenols, or diphenols, indole poliphenols,ciclodopa DHI Y DHICA1, quinones, semiquinones or hydroquinones.L-tyrosine, L-dopamine, morpholin, ortho benzoquinone, dimorpholin,porphirin black, pterin black, ommochrome black, free nitrogenprecursors, any of the above listed with any size or particles. (from 1angstrom to 3 or 4 cms.). All afore mentioned the compounds,electroactive, in suspension, solution, in gel, that absorb theultrasound in the interval of one MHz, natural or synthetic, withvegetal, animal or mineral origin; pure or mixed with organic orinorganic compounds, ions, metals, (gadolinium, iron, nickel, copper,erbium, europium, praseodymium, dysprosium, holmium, chromium ormagnesium, lead selenure, and so on). Gadolinium is a very effectivemetal. The metal is incorporated into the melanin in ionic form or as aparticle, as well as drugs or medication energizing the photoelectrochemical design with light (natural or synthetic, coherent ornot, monochromatic or polychromatic) with wavelength mainly between 200and 900 nanometers, though other wavelengths and other energy types, forexample, the kinetic, also are efficient in various grades, according tothe rest of the conditions (pH, temperature, pressure, and so on). Tothis kind of designs magnetic fields from soft to significant intensitycan be applied.

The events in this design may occur to a greater o lesser extent underinternal or external physical or chemical stimuli.

We propound the use of melanin (as mentioned before) as the electrolyzermaterial of the water molecule, using light as main or sole energysource, particularly at wavelength between 200 and 900 nm for thehydrogen production systems known as photoelectrochemical methods. Asaforementioned, these systems integrate a semiconducting material and awater electrolyzer inside a monolithic design to produce hydrogen atomsdirectly from water, using light as the main or sole source of energy,though sound, ultrasound, in an interval of one MHz, mechanical stir,magnetic fields, etc. can also be used.

Although, it is a simple concept, the challenge was to find a materialthat could withstand the whole process. At least two basic criteria hadto be met: one was the light absorbing system or compound had togenerate enough energy to start, lead and support completely theelectrolysis reaction, and it had to be low cost, stable and longlasting in a water environment.

Melanin, melanin precursors, melanin derivatives, melanin variants andanalogues can meet reasonably and efficiently the above mentionedrequirements and this represents a progress to solve the central problemof photoelectrochemical designs.

The shape of the container holding it in the appropriate equipment canbe very varied: cubic, cylinder, spherical, polyhedral, rectangular,etc. Being one of the main requirements, to be transparent, in order topermit the light to pass through and depending on the wavelength of theillumination that is going to be used, the walls could be made ofquartz, for example, so that the walls of the container do not absorbthe ultraviolet radiations, or if a specific wavelength is determined,the material of which the container is made could be of a color thatallow maximum transparency or absorption of the wavelength from theelectromechanical spectrum which we are interested in. The walls can bemade of glass or of any other polymer whose transmission characteristicsof the electromagnetic radiations fit to the final needs of thephotoelectrochemical design. The wavelengths that can be used toenergize the design comprise from 200 nanometers to 900 nanometers.

Inside the cell, the main material, the essential solute, melaninprecursors, melanin derivatives, melanin variants and analogues, mainlydissolved in water, because the basis of the design is the notablecapacity of melanin to capture photons of wavelengths comprised between200 and 900 nm, probably by the surrounding portions of the molecule,followed by the generation of high energy electrons from low energyelectrons. These high energy electrons go to the centers of freeradicals of the compound where they are probably captured by an elementfor example: a metal such as iron, copper, gadolinium, europium, etc.from where they are transferred to a primary electron acceptor from anature that is uncertain up to now because the union is complex andcomprises ionic interactions depending on the pH. This electron transferliberates energy which is used to establish the protons gradient.

The combination of the melanin molecule with water forms what can becalled a photosystem, which captures luminous energy using at least twointerrelated activities: removal of electrons from water and generationof a protons gradient.

The melanin components are in very close contact among them which makesa fast transfer of energy easy. At three picoseconds of illumination,the melanin reaction centers respond transferring a photo-excitedelectron to the primary electron receptor. This transference ofelectrons generates a donator, positively charged and a receivernegatively charged. The importance of the formation of two species withopposite charges is seen when we consider the reduction capacities ofthese two species, because one of them is deficient in electrons and canaccept electrons which makes it an oxidizing agent. By contrast, theother compound has an extra electron that can be lost easily, making ita reducing agent. This event—the formation of an oxidizing agent and areducing agent from the light⁻ takes less than billionesimal of secondand is the first essential step in the photolysis.

Because they are charged in an opposite way, these compounds show anobvious mutual attraction. The separation of charges is (probably)stabilized by their movement to opposite sides of the molecule; beingthe negative compound the one that first gives its electron toward aquinone (Q1) and possibly then the electron is transferred to a secondtype of quinone (Q2), this producing a semi reduced form of the quinonemolecule which can be strongly linked to the reaction center of themelanin molecule. With each transfer, the electron gets closer to thereaction center of the melanin molecule. The portion of melaninpositively charged is reduced, thus preparing the reaction center forthe absorption of another photon. The absorption of a second photonsends a second electron along the way. (melanin negatively chargedtowards the first and second quinone molecule—Q1 and Q2 -). This secondmolecule absorbs two electrons, and thus combines with two protons. Theprotons used in this reaction could derive from the same melaninmolecule or from the surrounding water, causing a decrease in theconcentration of hydrogen ions of the photosystem, what contributes tothe formation of a protons gradient. In theory the reduced quinonemolecule is dissociated from the reaction center of melanin, beenreplaced reaction by a new quinone molecule. These reactions occur atnormal temperature but when you modify for example the temperature youcan favor the reaction in one or other way, depending on the control ofthe other variables: (pH, magnetic fields, concentrations, gases,partial pressures, shape of cells, etc.) and the main objective of theprocess.

The separation of water molecules into hydrogen and oxygen atoms is ahighly endergonic reaction due to the very stable association ofhydrogen and oxygen atoms. The separation of the water molecules (inhydrogen and oxygen atoms) in the laboratory requires the use of astrong electric current or high temperature of almost 2,000° C. theabove (water electrolyzing) is obtain by melanin at room temperature,using only the energy obtained from light, wavelength mainly comprisedbetween 200 and 900 nanometers, either from natural or artificialsource, coherent or not, concentrated or disperse, mono orpolychromatic. It is estimated that the redox potential of oxidized formof quinone is approximately +1.1 V, what is strong enough to attract thefirmly united low energy electrons from the water molecule (redoxpotential of +0.82), separating the molecules in hydrogen and oxygenatoms. The separation of the water molecule by photopigments is namedphotolysis. It is believed that the formation of the oxygen moleculeduring the photolysis requires the simultaneous loss of four electronsfrom two water molecules according to the reaction:2H₂O

4H⁺+O₂+4e ⁻

A reaction center can only generate a positive charge or its oxidizingequivalent at the same time. This problem is solved hypothetically bythe presence of four nitrogen atoms in the reaction center of themelanin molecule, each one of them transferring only one electron. Thisnitrogen concentration, adds may be four positive charges upontransferring four electrons (one each time) to the closest quinone⁺molecule.

The transfer of electrons from the nitrogens of the reaction centers tothe quinine³⁰ is obtained by means of the passage through a positivelycharged tyrosine moiety. After each electron is transferred to quinone⁺,regenerating quinone, the pigment is reoxidized (again a quinone⁺) afterthe absorption of another photon to the photosystem. So the accumulationof four positive charges (oxidizing equivalents) by the nitrogen atomsof the reaction center is modified by the successive absorption of fourphotons by the melanin photosystem. Once the four charges have beenaccumulated the oxygen releasing quinone complex can catalyze the 4e⁻removal from 2H₂O forming an O₂ molecule, and regenerating the totallyreduced quantity of nitrogens in the reaction center.

The protons produced in the photolysis are released in the medium wherethey contribute to the protons gradient. The photosystem must beilluminated several times before the occurrence of O₂ release and thushydrogen can be measured; this indicates that the effects of theindividual photo reactions must accumulate before O₂ and hydrogen arereleased.

The quinones are considered carriers of mobile electrons. It is to bekept in mind that all electron transfers are exergonics and occur as theelectrons are successively taken to carriers with an increasing affinityfor the electrons (more positive redox potentials). The need of havingelectron moving carriers is obvious. The electrons generated by thephotolysis can pass to several inorganic receivers, which are thusreduced. These ways for electrons can lead (depending on the compositionof the used mix) to the eventual reduction of nitrate molecule (NO₃)into ammoniac molecule (NH₃) or the sulphates in sulphydrides (SH⁻)reductions that change the inorganic wastes into compounds necessary forlife. So the sunlight energy can be used not only to reduce the mostoxidized form of a carbon atom (CO₂) but also to reduce the mostoxidized forms or nitrogen and sulphur.

The production of one O₂ molecule requires the removal of four electronsfrom two molecules of water, the removal of four electrons from waterrequires the absorption of four photons, one for each electron.

The design of the cell is an important parameter for the optimization inobtaining the product of the reaction in which we have a particularinterest, because the addition of electrons, the nature of them, the useof magnetic fields, the addition of several compounds (organic orinorganic, ions, metals, drugs or medications) to the photosystem thatat the beginning was only melanin and water, plus the addition ofelectrolytes, plus the addition of medicines, and temperaturemanagement, the control of partial pressures of gases, the management ofthe electrical current generated, the application of magnetic fields,the level of pH, the material used in making the cells and the shape anddisposition of its internal divisions, etc. Apart from other variables,which are able to be controlled in such a way that the final design canrecover electrons, or protons, or oxygen, and the resulting compoundsaccording to the formulation of the medium in the melanin is dissolved.Thus, the melanins, melanin precursors, melanin derivatives, melaninvariants and analogues (its analogues, its synthetic or naturalprecursors, pure or combined with organic compounds and inorganiccompounds, metals) allow a notable flexibility of the design accordingto the goals to reach.

The optimization of photoelectrochemical design relates to theobjectives, for example: for a higher generation of protons and oxygenor generation of electricity; the largest possible area of exposition ofthe liquid compound to the light in an extended container, apart fromother procedures such as the addition of electrons carrier compounds,melanin doping, or positive microlens to concentrate the light, etc.

The design of the container is not limited and can have a spherical,cubic, rhomboidal, polyhedric, plain concave, plain convex, biconvex,biconcave shape with microlens in a side (the side exposed to light toconcentrate it) and flat on the other side cylindrical, circularcylindrical, hollow cylindrical, circular cone (straight) truncatedcone, rectangular prism, oblique prism, rectangular pyramid, straighttruncated pyramid, truncated spherical segment, spherical segmented,spherical sector, spherical with cylindrical perforation, sphere withconic perforations, torus (circular section ring), cylinder with slantedcut, cylindrical wedge, semi prism barrel, and combinations of them,etc, because the liquid assumes any shape, only requiring to betransparent to allow the passage of the maximum possible light, anddepending of the kind of melanin used (doped or not, for example), itwill be convenient to select a specific wavelength to illuminate thesoluble melanin, but until this moment one of the big virtues of solublesynthetic melanin is that it absorbs the majority of the wavelengths inthe electromagnetic spectrum. But it appears to show its majorabsorption between 200 and 900 nanometers wavelengths. The control ofthe partial pressures of the gases in the interior of the cell is animportant variable, and depending on the cell shape and the use given toit, these pressures can go from 0.1 mm Hg until 3 or 4 atmospheres;another variable that must be taken into account is the concentration ofdifferent substances dissolved in the liquid, where the criticalconcentration is mainly of melanin and can go from 0.1% to 100%, theincrease could be in steps of 0.1%; other variable that can be modifiedis the ratio among the different components of the formula (depending onthe use), because potassium can be added in a concentration from 0.1 to10%; sodium in a concentration from 0.1 to 10%; chlorine in aconcentration from 0.1 to 10%; calcium in a concentration from 0.1 to10%; iron in a concentration from 0.1 to 8%, copper in a concentrationfrom 0.1 to 5%, arsenic in a concentration from 0.1 to 8 or 9%, gold ina concentration 0.1 to 8 or 9%, silver in a concentration similar togold, nickel in a concentration from 0.1 to 8%, gadolinium, europium,erbium, etc.

The final volume can range from 1 microliter to 10 or 20 litersdepending on the size of the container and the available space; thetemperature can fluctuate from 2 to 45° C., the frequency of change ofsolution can be from every 15 minutes to several months or 2 or 3 years;the formation of compartments inside the little cell, in the interior ofthe cell shapes ranging from small spheres (microspheres, there can beseveral dozens of them) to spheres the size of which could be included 3or 4 times inside the whole design, and in the shape of the interior ofthe little cell cubic rhombic, polyhedral, concave plane, convex plane,biconvex, biconcave with microcells, biconvex on one side (the sideexposed to light to concentrate it) and flat on the other side,cylindrical, circular cylindrical, hollow cylindrical, circular cone(straight), truncated cone, rectangular prism (straight), oblique prism,rectangular pyramid (straight), truncated pyramid, truncated sphericalsegment, spherical segment, spherical sector, spherical with cylindricalperforation, sphere with conic perforations, toro (circular sectionring), cylinder with slanted cut, cylindrical wedge, barrel, semiprism,can be used including combinations of these, the power of the microlenscan range from 0.1 to 100 diopters, the redox properties of thematerials used in the formation of the compartments (iron, silver,copper, nickel, gold, platinum, gallium arsenide, silicon, gadolinium,europium, erbium, praseodymium, dysprosium, holmium, chromium,magnesium, lead selenide and alloys of them, etc).

The use or not of cathodes y anodes, their material (for exampleplatinum, iron, silver, gold, steel, aluminum, nickel, arsenium,gadolinium, europium, erbium, praseodymium, dysprosium, holmium, chromo,magnesium; gallium), depending on the optimal characteristics to recoverelectrons or hydrogen, but it has to be kept in mind that in presence ofmetal or borium, the hydrogen works with −1; another variable is initialpH of the solution that can range from 2 or 3 to 8 or 9 units of pH,being the most used about 7, the above mentioned variables that can behandled in order to control the photoelectrolysis process depending onthe needs of the project in question.

The core of any efficient photoelectrochemical designs are the melanins,i.e. melanin, melanin precursors, melanin derivatives, melanin variantsand analogues, water soluble, where they catalyze the photolysisprocess, without undergoing significant changes except the presence ofelements such as magnesium, iron, copper, lead, and others, theresulting products of which together with the resulting products of thepartial reduction of the oxygen atom (superoxide anion, hydroxylradical, hydrogen peroxide, quinones and orthoquinones), can fast orslowly damage the effectiveness of melanin, but in the case of puremelanin, at a 10% concentration, for example, the duration of thecompound is long enough to be economically convenient (years), and thesynthesis of melanin is a very efficient process. Thus, from an economicand ecological point of view it is very viable, because pure melanin isfully biodegradable. Thus, the little cell only requires a periodicsupply of distillated water, as well as a periodic replacement ofsoluble melanin, or eventually, the renewal of substances added to thedesign to optimize or potentiate some of the processes occurring as aresult of exposing the photo-electrochemical design to the light. Theecological advantage of the final products of the reaction being watermolecules, oxygen molecules or atoms, hydrogen, high energy electrons,and electrical current can be easily realized. There is littlegeneration of greenhouse effect CO₂ molecules. The transfer of electronsreleases energy, which is used to establish a proton gradient.

The proton movement during the electrons transportation can becompensated by the movement of other ions, so using membrane and asolvent with adequate solutes, membrane potential can be formed fromphotons capture by mean of melanin.

The electrolyzing properties of melanin (among many others) can explainthe light generated peak observable in the electroretinogram, because ifmelanin is illuminated, intracellular pH gets down, that activates thechlorine channels sensitive to pH in the basolateral cellular membrane.(The light peak is an increase of the potential that follows the FOTphase (fast oscillation trough) and forms the slowest and longestlasting component of the electroretinogram from direct current. (Kris1958, Kolder 1959, Kikadawa 1968, Steinberg 1982).

Melanins, melanin precursors, melanin derivatives, variants andanalogues, oxidize the water molecule to O, O₂, and H₂, absorbing energyobtained by the light (photons), and reduce oxygen atom with hydrogenatoms to H₂O, liberating energy (electricity, although it can “keep” theelectricity, i.e. it can function as a battery or accumulator, i.e. notonly generating energy but also keeping it for a while and within somelimits). That is why the cell design can be adapted to the requirements.

H₂ and O₂ atoms are produced with light, but the generation of theseelements can be increased by melanin doping (melanin, its precursors,variants, derivatives, or synthetic or natural analogues) with metals oradding organic and inorganic molecules, also modifying the electrolyteconcentrations, adding drugs or controlling the characteristics oflight, over the liquid containing water and melanins (melanin, itsprecursors, variants, derivatives, or synthetic or natural analogues),for example with a design based on microlens to condensate or selectingdeterminate wavelength, using coherent or disperse, monochromatic,polychromatic, continuous, discontinuous, natural, artificial, light;etc. The photoelectrochemical reactions happen in two ways, i.e. thewater molecule is separated but also formed, so it can recover electriccurrent of the design and it can also be optimized through melanindoping with different substances (drugs, metals, electrolytes, organicand inorganic molecules, and others) or by light concentration by meanof lens, among others.

The box containing the liquid can have different shapes that adapt todifferent needs, in the house roofs, car roofs, plants buildings,industrial processes, etc. cells connected among them, but the centralcomponent of the design is melanin (melanins, its precursors, itsderivatives, its variants, its analogues, water soluble), that inducesand carries out the photolysis of the water molecule, in presence oflight.

The melanins, melanin precursors, melanin derivatives, melanin variantsand analogues remove electrons from water and generate a gradient ofprotons.

The light depending reactions can also generate energy to reduce CO₂ toCH₂O, nitrates to ammonia and sulphates to sulphydriles.

A compound that has been reported in the literature and that has shownto induce and carry out these processes is the chlorophyll but becauseit absorbs light mainly in the extreme regions of the visible spectrum,it is estimated that 80% of the irradiated energy is wasted, incontrast, with our offer to use melanin, because it practically absorbssoft and hard ultraviolet electromagnetic radiations, all the visiblespectrum and the far and near infrared lengths (Spicer & Goldberg 1996).It would not be surprising that it could absorb other types of energysuch as kinetic energy or other wavelengths of the electromagneticspectrum.

EXAMPLES

We conducted small scale experiments. Once we inferred these interestingproperties of melanins according the structure activity relation, weplaced soluble synthetic melanin in water, forming a 1% solution in five20 mL transparent, high density polythene flasks, at room temperature.We measured the pH before and after lighting them during 30 minutes withvisible light of natural source (sun) not concentrated; measuring thepH, we obtained in average a decrease of two decimals of unit of pH(from 7.3 to 7.1), we consider it significant because melanins havebuffering property per se, so the change must be larger, but is hiddenby melanin intrinsic buffering property, and thus we only detected partof this pH modification, a change of pH the magnitude of which isrelated to the biological system, because if it were greater, it wouldprobably severely destroy or damage the cell, but a change of this sizeis enough to induce biological changes that involves said extraordinarycompound. To determine the biological magnitude of a decrease of 0.2units of pH, we will mention that, in the case of blood, this reductionincreases more than 10% the calcium concentration.

Besides, the total blood pH ranges from 7.38 to 7.44, the arterial bloodpH ranges from 7.36 to 7.41, and the vein blood pH ranges from 7.37 to7.45, i.e., the variations are within a very narrow margin, and thus adifference of 2 decimals of unit of pH is really significant in abiological system.

In an initial close design we estimated the liberation of hydrogen infunction of electric current generation, and obtained 50 mV on averageand 110 mV between each peak, corresponding to about one to two units ofpH, what is equivalent to the production of 1×10⁻⁷ mol/liter of hydrogenper each pH unit, because the molecular weight of hydrogen indicatesthat a mol of it is equal to a gram of hydrogen.

On the other hand, the melanocyte, is the cell showing most affinity forcalcium in the organism, showing an affinity one thousand times higherthan the bone, because although the latter has a larger quantity, it isonly deposited in mineral form.

It is to be noted that this change from 0.2 to 1.0 units of pH, as wellas its reversion when they were placed in flasks in a dark place, wasforeseen by our theoretical system, i.e. when we made the experiment weknew the result we were going to obtain, in other words, we did not makemany experiments, we only made it twice or three times, resulting as weexpected. The solutions of melanin used in the experiments had beenprepared for at least 3 years, were not doped; and as pointed out by thetheoretical system, it is a very long lasting compound, very stable inwater, that does not require preservatives, or refrigeration, is notcontaminated with microorganisms despite the age of the preparation, andthese solutions only need to be kept in a fresh and dry place; that iswhy we were relatively sure that the reaction was going to happened,though we could not foresee its magnitude because the buffering capacityof melanin is not known or it is not possible to assess it exactlybecause the melanin formula is not fully known.

This experiment also demonstrated that melanin does not requirepreservatives and its electrolyzing properties are maintained despitethe time (3 years after being synthesized). We are now working onimproving the protocols to answer to some of the many questions that aregenerated through these experiments, but because of the extraordinarypossibilities of industrial, medical, energetic, and laboratoryapplications of the electrolyzing characteristics of melanin, we decidedto protect immediately its use in the photoelectrochemical processes ofenergy generation.

A photoelectrochemical system was built that works with natural light,the reactive cell of which contains up to 1.3% of melanin, i.e. morethan 98% is water. Optionally metals or drugs can be used to increaseits efficiency. The little cell has been hermetically sealed to avoidthat gases generated escape. Another variable refers to the electrodes,their geometry and nature that can be conductors, semiconductors orsemimetals. Each millimeter of electrolyzing material has produced 10millivolts and microampers day and night, during years, recharges ofelectrolyzing material or water have not been required; it has beenconducted at room temperature showing that it is an efficient,economical and versatile photolectrochemical system.

In this example, we managed to light the first light emitting diode(LED), which remains lit six months later. The cells do produceelectricity and we are working on making them more efficient and scalingthem up to competitive costs. Initially, we used a concentration of 1.3%melanin and 98.7% water. Later, when we increased the concentration ofmelanin to 4%, the generation of electricity increased exponentially. Interms of technological development, we have achieved progress I considerto be significant and which can reflect the potential of such cells.

Besides, we were able to connect up a small music player, since eachcell now produces 600 mV and 200 mA, that is, a thousand times more thanthe 200 μA we used to achieve.

We have produced a liter and a half of melanin every three months andour cells were of 30 mL and produced 400 mV and 10 μA. However,currently, in our small laboratory, we produce about 200 liters ofmelanin daily.

I claim:
 1. A device for performing a photoelectrochemical process togenerate energy, the device comprising: a cell containing an aqueoussolution of at least one water electrolyzing material, each of the atleast one water electrolyzing materials present in the aqueous solutionbeing a water-soluble water electrolyzing material selected frommelanin, melanin precursors, melanin derivatives, melanin analogues, andmelanin variants; a source of energy; and a pair of electron receivingelectrodes.
 2. The device according to claim 1, wherein the source ofenergy is selected from natural light, artificial light, electromagneticwaves, radio waves, and gamma rays.
 3. The device according to claim 2,wherein the source of energy is light energy and the device furthercomprises a lens to concentrate the light energy.
 4. The deviceaccording to claim 3, wherein a surface of the lens exposed to the lightenergy is biconvex.
 5. The device according to claim 4, wherein a powerof the lens is in a range of 0.1 to 100 dioptres.
 6. The deviceaccording to claim 1, wherein the water-soluble water electrolyzingmaterial comprises melanin.
 7. The device according to claim 1, whereinthe water-soluble water electrolyzing material is doped with a metal oran organic or inorganic compound.
 8. The device according to claim 1,wherein the source of energy is light energy having a wavelength in arange of 200 to 900 nm.
 9. The device according to claim 8, wherein thelight energy is natural light.
 10. The device according to claim 1,wherein the aqueous solution has a pH in a range of 2 to
 9. 11. Thedevice according to claim 1, wherein the device functions as a batteryor accumulator.
 12. The device according to claim 1, wherein magneticfields are applied to the cell.
 13. The device according to claim 1,wherein the cell is made of a material that permits transmission ofelectromagnetic waves for activation of the process.
 14. The deviceaccording to claim 13, wherein the cell is made of glass orpolyethylene.
 15. The device according to claim 1, wherein the cell issegmented.
 16. The device according to claim 1, wherein the cell is aclosed cell.
 17. The device according to claim 1, wherein partialpressures of gases formed within the cell are in a range of 0.1 mm Hg to4 atmospheres.